Which of the following is NOT a type of CNC milling machine?

The choice of the vertical lathe as the answer is based on the fact that it is not classified as a type of CNC milling machine. While vertical milling machines, horizontal milling machines, and CNC routers are all designed specifically for milling operations, which involve removing material from a workpiece using rotary cutters, a vertical lathe serves a different purpose altogether.

A vertical lathe is a type of CNC machine used primarily for turning operations, where the workpiece is rotated against a stationary cutting tool to shape it. This is typically done to create cylindrical parts and components. In contrast, milling machines perform operations that involve complex shapes and features that require the workpiece to be held stationary while the cutter moves across its surface.

Therefore, recognizing the function of each machine helps clarify the distinction between a vertical lathe and various types of CNC milling machines. Understanding this classification is essential for selecting the appropriate equipment for specific machining tasks.